Silane compounds such as monosilane and disilane are used in a variety of applications. In the field of semiconductors, silane compounds are frequently used as starting materials for the production by chemical vapor deposition (CVD) of silicon-based dielectric films of, e.g., silicon nitride, silicon oxide, or silicon oxynitride. More specifically, silane compounds can produce silicon nitride by reaction with a nitrogen-containing reaction gas such as ammonia, silicon oxide by reaction with an oxygen-containing gas such as oxygen, and silicon oxynitride by reaction with a nitrogen-containing gas and an oxygen-containing gas.
At present the standard method for producing silicon nitride films by CVD involves inducing a reaction between ammonia gas and dichlorosilane (=the silane compound); however, ammonium chloride is produced as a by-product by this reaction. Ammonium chloride is a white solid and as such accumulates in and clogs the exhaust lines of the CVD reaction apparatus. A CVD method is therefore required in which the starting material is a chlorine-free silane compound. It is also desirable during the production of silicon nitride, etc., by CVD technology to obtain good film-deposition rates at low temperatures (at or below 600° C.).
Tetrakis(dimethylamino) silane and tetrakis(diethylamino) silane may be used as chlorine-free silane compounds, but these aminosilane compounds suffer from being usually of low quality (high amount of impurities) and from providing slow film-deposition rates at low temperatures.
The chlorine-free alkylaminodisilanes are also known. These alkylaminodisilanes are solid at ambient temperatures. For example, hexakis(dimethylamino) disilane is reported to undergo sublimation at 230° C. under reduced pressure. Compounds that are solids at ambient temperature have poor handling characteristics.